In modern automotive headlighting, a strong trend goes to adaptive systems where the light distribution can be changed dynamically. For example, one would like to have a high-beam pattern, but with a well-defined and moving dark section to spare out an oncoming car, to avoid glare. Or one would like to illuminate a given road sign, or an obstacle that, for example, a camera of a car could have detected.
Technically, such systems can be realized with different approaches, with increasing performance, but also complexity: switchable mechanical apertures, LED matrix lights, micro displays (as in beamers), or laser scanners. The principle of the laser scanner comprises a strong blue laser beam which can be electronically switched and direction-controlled by a small mirror, typically a MEMS (micro electromechanical system). In this way, it is quickly steered over a converter or phosphor surface of a light conversion module where it is partially converted to yellow light, which adds up with the remaining blue light to form white light. If the movement of the white-light spot on the phosphor is fast enough, it is perceived as a steady white-light distribution or image. This image is then projected onto the road through a lens. By a suitable control of the mirror movement, synchronized with a suitable switching of the laser beam (on and off, different intensities), a large variety of images on the phosphor—and thus light distributions on the road—can be created.